Catalytic isomerization



' Patented May 22, 1945 2,310,509 car-Anglo rsommrza'non Alexander N.. Sachaneu, Woodbury, and Philip D. Caesar, Wenonah, N. 1., alignora to 8000117- Vacuum Oil Company, Incorporated, a corpo- Original application August 30, 1941, Serial No. 408,995.

ration of New York No Drawing.

Divided and this application August 18, 1944, Serial No. 550,129

12 Claims. (01. 260-4035) This invention relates to catalytic hydrocarbon reactions, and more particularly it has reference to reactions of hydrocarbon materials catalyzed to as activators for the catalyst, without the function thereof being understood. These previously used activators have an effect on the catalytic activity of the catalyst, but it is necessary to constantly supply these activators of the prior art in order to obtain what efiect they have. v

This invention is based upon the discovery that non-volatile or slightly volatile strong acids and acid chlorides, in general, when present in substantial amounts, are suitable for the purpose of activating catalysts of the class to which the invention relates, which class is frequently referred to as "catalysts of the Friedel-Crafts type, viz., catalysts utilized in the classical Friedel-Crafts reaction. The'halides of aluminum, zinc, iron, zirconium, tin, beryllium, tantalum, and boron are generally suitable for the purposes of the invention and are the more important catalysts of the Friedel-Crafts type. For the purposes of this discussion, it may be A assumed that aluminum chloride is typical of the class, and reference to that prominent member of the groupis to be understood as generally applying to all members thereof.

The invention contemplates the provision of an improvement in hydrocarbon reactions involving catalysis by aluminum chloride through '15 acid. The latter substances have been referred the use of a novel and extremely emcient activaprocesses. We prefer to use the temperatures from 0 C. to C. because these moderate temperatures favor the formation of higher octane number alkylatesu In addition to this, our copending patent application Serial No. 404,046, shows that above 60 C. the use of activators is not necessary, the high temperature itself being an activating factor.

The activators which have been found to possess the novel-and useful properties contemplated by the invention may be defined as those acid halides and strong acids, both organic and inorganic, which are substantially non-volatile under the conditions under which the reaction is conducted. Typical compounds to be used as activators according to the invention are such organic acids as trichloracetic; the inorganic acids, sulfuric and chlorosulfonic; and the acid halides, acetyl chloride and sulfonyl chloride.

Example I The nature of the invention is well-illustrated by the alkylation of isobutane with amylene at 40 C. A bomb was charged with 480 cc. isobutane, 39 grams aluminum chloride (10 per cent by weight of the total charge), and 11 grams trichloracetic acid. One hundred-fifty cc. of amylene were then pumped into the bomb at 40 C. under a pressure of about 71 to 79 pounds per square inch with vigorous stirring of the mass. The total time of reaction was about 11% hours, at the end of which time the synthetic paraflinic constituents of the reaction mass were separated as yield and evaluated. It was found that a total yield of 230 cc. of stabilized gasoline containing 91 per cent of fractions boiling in the range of aviation gasoline (up to C.) was obtained. The iodine number of the gasoline was zero; specific gravity, 0.670; and octane number (Motor method), 82.4.

One important aspect of this invention lies in the discovery that the proportion of the activator has a material eflfect. The table set out belowpresents the results of a series of alkylation runs conducted in accordance with the method of Example I. The conditions of reaction, with the exception 01 proportions of activator, were maintained constant. In each run' isobutane was alkylated at 50 C. with amylene in the presence of 10 per cent aluminum chloride (based upon weight of total charge) ac- Cara-a sa "as.

e cpr u with res t with res to A] to my theoretical (per cent by cent by weight) vol.)

It has been found that best results are obtained by using trichloracetic acid as an activator for aluminum chloride when the activator is present in an amount equal to about 30 per cent of the catalyst. The drop in eificiency at higher concentrations, although much less than the corresponding drop at concentrations below the preferred amount, is very noticeable, as shown by the foregoing table. Other combinations of catalyst and activator within the scope of the invention show similar properties. Similar results are alsoobtained in other processes comprising hydrocarbon reactions involving the use of catalysts of the class to which this invention relates-such as,

for example, isomerizatlon.

In general, the activators of this invention should be present in amounts not substantially less than 10 per cent by weight (based upon catalyst) for best results. It will be at once apparent that reactions involving the use of hydrochloric acid, and other volatile acids, as an activator for catalysts of the class typified by aluminum chloride cannot be conducted in accordance with the present invention without the use of considerably higher pressures than have been heretoi'ore usual in the art. The relatively high concentrations required are not possible except when a pressure in excess of the vapor pressure of the acid. or a pressure suflicient to cause the volatile activator to have a density which makes it possible to maintain at least about 5 per cent of activator in the reaction mixture, is applied. For that reason the preferred class of activators are those which may be referred to as strong acids and acid halides, which are non-volatile at usual operating pressures, i. e., pressures not substantially in excess of about 700 pounds per square inch.

Example II The present process has also proved very satisfactory in the alkylation of isobutane withethylene. The alkylate so formed contains as much as per cent of di-methyl butanes, predominantly 2,3,di-methyl butane. In producing that high-grade product the following procedure has been used:

Seventy grams ethylene were pumped gradually specific gravity, 0.655; iodine number, zero; and octane number by the Motor method, about 90.0.

Although the foregoing examples describe the use oi -aluminum chloride in conjunction with trichloracetic acid, it will be apparent to those skilled in the art that other catalysts of the specified class may be used in lieu thereof with comparable results. It has been found that the other activators described also give results very similar to those reported above. The acid activators of this invention belong to the group commonly referred to as strong acids. Related compounds, such as weak acids (typified by acetic acid) and anhydrldes (as acetic anhydride) do not activate aluminum chloride to a sufllcient extent to be of value in the production of synthetic paramnic hydrocarbons by alkylation. Similarly, polymerization of olefins by aluminum chloride is not enhanced to a very great extent by the use of acetic acid, acetic anhydride or like compounds in the reaction mixture. Although the present activated catalysts are of considerable value in polymerization reactions, it is' still possible to cause the alkylation to proceed to the material exclusion of polymerization at the higher temperatures.

Example III by the alkylation of isobutane with ethylene in the presence of 6 per cent aluminum chloride and an amount of sulfuric acid equal to 30 per cent of the weight of catalyst at 28 C. A crude yield equal to '73 per cent of the theoretical was obtained, of which was in the aviation gasoline boiling range, having an octane number of 89 and an iodine number of zero.

It is not to be assumed that the specific examples relating to alkylation of lower molecular weight aliphatics exhaust the field of the invention. Those other hydrocarbon reactions involving the use of a catalyst of the nature of aluminum chloride are also benefited. Alkylation of relatively high molecular weight aliphatic hydrocarbons and aromatic compounds is also improved by utilizing the principles disclosed herein. Further, such reactions as decomposition of heavy branched-chain hydrocarbons to lighter materials are also benefited.

Example IV- Example V Isomerization reactions catalyzed'with 10% aluminum chloride activated by 30 per cent (based upon catalyst weight) of trichloracetic acid give very good results. Normal butane, treated at C. and 600 1b. pressure for three hours with 10 per cent catalyst, yielded 30 per cent isobutane and 3 per cent isopentane.

Example VI The process of Example V using 5 per cent of catalyst gave 16.3 per cent isobutane, while the greater portion of the remainder (74 per cent) was found to be normal butane suitable for recycling.

Example VII Normal pentane treated at 100 C. for 1% hours with the catalyst and activator of Example V yielded 40 per cent isobutane and 26 per cent isopentane, indicating that the simultaneous effect of isomerization and cracking.

Example VIII An autoclave provided with a stirrer was charged with 250 grams of normal pentane, 26 grams of aluminum chloride and 8 grams of chlorsulfonic acid. The mixture was reacted at 100 C. for one hour with constant agitation. The product was of the following composition:

Per cent by weight Isobutane 36 Isopentane 29 n-Pentane l6 {I'he remainder, including hydrocarbons of the comprises conducting the reaction in the presence of trichloracetic acid.

3. In a process of isomerizing normal paraflln hydrocarbons by reaction thereof in the presence of a catalyst of the Friedel-Crafts type; the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amoimt of said acid being about 30 per cent of the amount of said catalyst by weight.

4. In a process of isomerizing normal paraflin hydrocarbons by reaction thereof in the presence of aluminum chloride, the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amount of said acid being about 30 per cent of the amount of said catalyst by weight.

5. In a process of isomerizing normal butane by reaction thereof in the presence of a catalyst of the Friedel-Crafts type; the improvement which comprises conducting the reaction in the presence of trichloracetic acid.

6. In a process of isomerizing normal butane by reaction thereof in the presence of aluminum chloride, the improvement which comprises conducting the reaction in the presence of trichloracetic acid.

7. In a process of isomerizing normal butane by reaction thereof in the presence of a catalyst of the Friedel-Crafts type; the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amount of said acid being about 30 per cent of the amount of said catalyst by eight.

8. In a pro of isomerizing normal butane by reaction thereof in the presence of aluminum chloride, the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amount of said acid being about '30 per cent of the amount of said catalyst by weight.

9. In a process of isomerizing normal pentane by reaction thereof in the presence of a catalyst of the Friedel-Crafts type; the improvement which comprises conducting the reaction in the presence of trichloracetic acid.

10. In a process of isomerizing normal pentane by reaction thereof in the presence of aluminum chloride, the improvement which comprises conducting the reaction in the presence of trichloracetic acid.

11. In a process of isomerizing normal pentane by reaction thereof in the presence of a catalyst of the Friedel-Crafts type; the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amount of said acid being about 30 per cent of the amount of said catalyst by weight.

12. In a process of isomerizing normal pentane by reaction thereof in the presence of aluminum chloride, the improvement which comprises conducting the reaction in the presence of trichloracetic acid, the amount of said acid being about 30 per cent of the amount of said catalyst by weight.

ALEXANDER N. SACHANEN. PHILIP D. CAESAR. 

